Tammy Evans-Strickfaden

Correlation of Human Immunodeficiency Virus Type 1 RNA Levels in Blood and the Female Genital Tract

In this study, the correlations of human immunodeficiency virus type 1 (HIV-1) RNA levels in blood plasma, vaginal secretions, and cervical mucus of 52 HIV-1-infected women were determined. The amount of cell-free HIV-1 RNA in blood plasma was correlated with that in vaginal secretions (Spearmans rank correlation coefficient (r) = 0.64, P<.001). In both blood plasma and vaginal secretions, the amounts of cell-free and cell-associated HIV-1 RNA were highly correlated (r=0.76, P<.01 and r=0.85, P<.01, respectively). Cell-free HIV-1 RNA levels in blood plasma and vaginal secretions were negatively correlated with CD4+ T lymphocyte count (r=-0.44, P<.01 and r=-0.40, P<.01, respectively). Similar to the effect observed in blood plasma, initiation of antiretroviral therapy significantly reduced the amount of HIV-1 RNA in vaginal secretions. These findings suggest that factors that lower blood plasma virus load may also reduce the risk of perinatal and female-to-male heterosexual transmission by lowering vaginal virus load.

Role of donor genital tract HIV-1 diversity in the transmission bottleneck

The predominant mode of HIV-1 infection is heterosexual transmission, where a genetic bottleneck is imposed on the virus quasispecies. To probe whether limited genetic diversity in the genital tract (GT) of the transmitting partner drives this bottleneck, viral envelope sequences from the blood and genital fluids of eight transmission pairs from Rwanda and Zambia were analyzed. The chronically infected transmitting partners virus population was heterogeneous with distinct genital subpopulations, and the virus populations within the GT of two of four women sampled longitudinally exhibited evidence of stability over time intervals on the order of weeks to months. Surprisingly, the transmitted founder variant was not derived from the predominant GT subpopulations. Rather, in each case, the transmitting variant was phylogenetically distinct from the sampled locally replicating population. Although the exact distribution of the virus population present in the GT at the time of transmission cannot be unambiguously defined in these human studies, it is unlikely, based on these data, that the transmission bottleneck is driven in every case by limited viral diversity in the donor GT or that HIV transmission is solely a stochastic event.

Progressive Infection in a Subset of HIV-1—Positive Chimpanzees

Chimpanzees are susceptible to infection with human immunodeficiency virus (HIV)-1; however, infected animals usually maintain normal numbers of CD4(+) T lymphocytes and do not develop immunodeficiency. We have examined 10 chronically infected HIV-1-positive chimpanzees for evidence of progressive infection. In addition to 1 animal that developed AIDS, 3 chimpanzees exhibit evidence of progressive HIV infection. All progressors have low CD4(+) T cell counts (<200 cells/microL), severe CD4:CD8 inversion, and marked reduction in interleukin-2 receptor expression by CD4(+) T cells. In comparison with HIV-positive nonprogressor chimpanzees, progressors have higher plasma and lymphoid virus loads, greater CD38 expression in CD8(+)/HLA-DR(+) T cells, and greater serum concentrations of soluble tumor necrosis factor type II receptors and beta2-microglobulin, all markers of HIV progression in humans. These observations show that progressive HIV-1 infection can occur in chimpanzees and suggest that the pathogenesis of progressive infection in this species resembles that in humans.

Correlation between Human Immunodeficiency Virus Type 1 RNA Levels in the Female Genital Tract and Immune Activation Associated with Ulceration of the Cervix

To address the hypothesis that local immune activation resulting from genital ulceration enhances human immunodeficiency virus type 1 (HIV-1) replication and shedding into the genital tract, paired plasma and cervicovaginal lavage (CVL) samples were obtained from 12 HIV-infected women before and after treatment of cervical intraepithelial lesions. Two weeks after treatment, inflammation and ulceration of the cervix were accompanied by major increases in mean concentrations of HIV-1 RNA (200-fold), tumor necrosis factor-alpha, interleukin 6, and soluble markers shed by activated lymphocytes and macrophages (sCD25 and sCD14, respectively) in CVL samples (P<.01 for each), but not plasma. Strong temporal and quantitative correlations were observed between concentrations of immunological markers and HIV-1 load in this compartment during a 10-week follow-up. Furthermore, in the presence of genital ulceration, HIV-1 in CVL samples was more readily captured by antibodies directed against virion-associated HLA-DR, a marker of host-cell activation, compared with virus in plasma. We suggest that local immune activation increases HIV-1 load in genital secretions, potentially increasing the risk of HIV-1 transmission.

Cellular Replication of Human Immunodeficiency Virus Type 1 Occurs in Vaginal Secretions

Most human immunodeficiency virus type 1 (HIV-1) transmission worldwide is the result of exposure to infectious virus in genital secretions. However, current vaccine candidates are based on virus isolates from blood. In this study, vaginal secretions from HIV-1-infected women were examined for evidence of cellular viral replication that produced virus with properties different from that in blood. Multiply spliced HIV-1 messenger RNA, which is found only in cells replicating virus, was detected in all vaginal lavage samples tested. There was a strong correlation between the amounts of multiply spliced HIV-1 messenger RNA and of cell-free HIV-1 RNA in the lavage samples. In addition, significant genotypic differences were found in cell-free virus from matched blood plasma and vaginal secretions. Moreover, drug resistance-associated mutations appeared in plasma virus several months before appearing in vaginal virus. These findings indicate that cellular replication of HIV-1 occurs in vaginal secretions and can result in a virus population with important differences from that in blood.

Rapid CD4+ T-Cell Loss Induced by Human Immunodeficiency Virus Type 1NC in Uninfected and Previously Infected Chimpanzees

ABSTRACT To investigate the pathogenicity of a virus originating in a chimpanzee with AIDS (C499), two chimpanzees were inoculated with a plasma-derived isolate termed human immunodeficiency virus type 1NC (HIV-1NC). A previously uninfected chimpanzee, C534, experienced rapid peripheral CD4+ T-cell loss to fewer than 26 cells/μl by 14 weeks after infection. CD4+ T-cell depletion was associated with high plasma HIV-1 loads but a low virus burden in the peripheral lymph node. The second chimpanzee, C459, infected 13 years previously with HIV-1LAV, experienced a more protracted course of peripheral CD4+ T-cell loss after HIV-1NCinoculation, resulting in fewer than 200 cells/μl by 96 weeks postinoculation. The quantities of viral RNA in the plasma and peripheral lymph node from C459 were below the lower limits of detection prior to inoculation with HIV-1NC but were significantly and persistently increased after superinfection, with HIV-1NC representing the predominant viral genotype. These results show that viruses derived from C499 are more pathogenic for chimpanzees than any other HIV-1 isolates described to date.

Diversity, Divergence, and Evolution of Cell-Free Human Immunodeficiency Virus Type 1 in Vaginal Secretions and Blood of Chronically Infected Women: Associations with Immune Status

ABSTRACT Most human immunodeficiency virus type 1 (HIV-1) infections are believed to be the result of exposure to the virus in genital secretions. However, prevention and therapeutic strategies are usually based on characterizations of HIV-1 in blood. To understand better the dynamics between HIV-1 quasispecies in the genital tract and blood, we performed heteroduplex assays on amplified env products from cell-free viral RNA in paired vaginal secretion (VS) and blood plasma (BP) samples of 14 women followed for 1.5 to 3.5 years. Diversity and divergence were less in VS than in BP (P = 0.03 and P < 0.01, respectively), and divergence at both sites was correlated with blood CD4+ cell levels (VS, P = 0.05; BP, P = 0.01). Evolution of quasispecies was observed in 58% of the women; the loss or gain of quasispecies in VS or BP was always accompanied by such changes at the other site. In addition, sustained compartmentalization of quasispecies in VS was found for four women, even as CD4+ cell levels decreased to low levels (<50 cells/μl). Quasispecies changes over time were associated with fluctuations in CD4+ cell levels; concordant increases or decreases in VS and BP divergence had greater CD4+ cell level changes than intervals with discordant changes (P = 0.05), and women with evolving quasispecies had greater decreases in CD4+ cell levels compared to that for women who maintained the same quasispecies (P < 0.05). Thus, diversity, divergence, and evolution of cell-free HIV-1 in VS can be different from that in BP, and dynamics between their respective quasispecies are associated with changes in CD4+ cell levels.

HIV-1 RNA Rectal Shedding Is Reduced in Men With Low Plasma HIV-1 RNA Viral Loads and Is Not Enhanced by Sexually Transmitted Bacterial Infections of the Rectum

BACKGROUND Among human immunodeficiency virus (HIV)-infected men who have sex with men (MSM) taking combination antiretroviral therapy (cART), the impact of rectal sexually transmitted infections (STIs) on rectal HIV-1 shedding is unknown. METHODS Human immunodeficiency virus type 1 (HIV-1) RNA was quantified from rectal swabs collected for Neisseria gonorrhoeae (GC) and Chlamydia trachomatis (CT) screening of HIV-1-infected MSM. Correlations of STIs with rectal viral load were explored using multinomial regression modeling. HIV-1 coreceptor tropism was predicted from sequencing in a subset of men. RESULTS Thirty-one (39%) of 80 men (59 prescribed combination antiretroviral therapy [cART]) had HIV detected in 38 (42%) of 91 rectal swabs. Rectal HIV detection was associated with plasma virus loads above 3.15 log₁₀ copies/mL (95% confidence limit [CL] 2.73, 3.55) and paired rectal viral loads and plasma viral loads were correlated (Kendalls tau [τ] 0.68, Spearman rho [P] = .77). Rectal STIs and abnormal anal cytology were not associated with rectal viral load. HIV coreceptor distribution was very similar between the plasma and rectum in 3 of 4 men. CONCLUSIONS Plasma and rectal viral load were correlated, and rectal STIs did not increase the likelihood of detecting HIV in the rectal secretions in MSM, including those with low or undetectable plasma viral load. Suppressing plasma viral load is likely to reduce risk of HIV transmission to insertive partners.

Novel preclinical models of topical PrEP pharmacodynamics provide rationale for combination of drugs with complementary properties

BackgroundThe limited success of recent HIV topical pre-exposure prophylaxis clinical trials highlights the need for more predictive models of drug efficacy that better simulate what may happen during sexual exposure. To address this gap, we developed complementary in vitro models to evaluate the ability of drugs to retain anti-HIV activity if cells were washed with seminal plasma (simulating what may happen following exposure to ejaculate), and to protect drug-naive T cells (representing newly recruited immune cells) co-cultured with explants that had been pretreated with drug. We focused on tenofovir disoproxil fumarate (TDF), the non-nucleoside reverse transcriptase inhibitors dapivirine (DPV) and IQP-0528, and the entry inhibitors maraviroc (MVC) and the D-peptide chol-PIE-12 trimer (PIE12). Studies were extended to macaques and the ability of cervical biopsies obtained from animals treated with an intravaginal ring formulation of IQP-0528 to protect ex vivo co-cultured T cells was determined. The antiviral activity of cervicovaginal lavage samples against a primary Clade C isolate was also measured and correlated with drug levels.ResultsCells exposed to TDF were equally protected from HIV whether or not the drug-treated cells were washed with medium or seminal plasma prior to challenge. In contrast, several-fold higher concentrations of NNRTIs and entry inhibitors were needed to attain similar levels of HIV inhibition following a wash with seminal plasma. Conversely, the NNRTIs and PIE12, but not TDF or MVC, were effectively transferred from ex vivo treated explants and protected co-cultured T cells. Biopsies obtained from IQP-0528 ring-treated macaques also protected co-cultured T cells with viral inhibition ranging from 42-72%. Antiviral activity correlated with the concentration of drug recovered. Combinations of TDF with IQP-0528 protected in both in vitro models.ConclusionsTogether, these models suggest that intracellularly retained drugs such as TDF may protect resident immune cells following coitus but sustained delivery may be required to protect immune cells subsequently recruited into the genital tract. Sustained delivery may also be critical for NNRTIs, which are rapidly transported out of cells and could be lost following sexual intercourse. An ideal approach may be a combination of drugs with complementary bioavailability profiles formulated for sustained delivery.

UC781 Microbicide Gel Retains Anti-HIV Activity in Cervicovaginal Lavage Fluids Collected following Twice-Daily Vaginal Application

ABSTRACT The potent nonnucleoside reverse transcriptase inhibitor UC781 has been safety tested as a vaginal microbicide gel formulation for prevention of HIV-1 sexual transmission. To investigate whether UC781 retained anti-infective activity following exposure to the female genital tract, we conducted an ex vivo analysis of the UC781 levels and antiviral activity in cervicovaginal lavage (CVL) fluids from 25 Thai women enrolled in a 14-day safety trial of twice-daily vaginal application of two concentrations of the UC781 microbicide gel. CVL samples were collected from women in the 0.1% (n = 5), 0.25% (n = 15), and placebo (n = 5) gel arms following the first application of gel (T15 min) and 8 to 24 h after the final application (T8-24 h) and separated into cell-free (CVL-s) and pelletable (CVL-p) fractions. As UC781 is highly hydrophobic, there were significantly higher levels of UC781 in the CVL-p samples than in the CVL-s samples for the UC781 gel arms. In T8-24 h CVL-p samples, 2/5 and 13/15 samples collected from the 0.1% and 0.25% UC781 gel arms, respectively, efficiently blocked infection with ≥4 log10 50% tissue culture infective dose (TCID50) of a CCR5-tropic CRF01_AE HIV-1 virus stock. Independent of the arm, the 11 CVL-p samples with UC781 levels of ≥5 μg/CVL sample reduced infectious HIV by ≥4 log10 TCID50. Our results suggest that the levels and anti-infective activities of UC781 gel formulations are likely to be associated with a cellular or pelletable component in CVL samples. Therefore, cellular and pelletable fractions should be assayed for drug levels and anti-infective activity in preclinical studies of candidate microbicides.